Various kinds of herbicides have been developed so far and have contributed to agricultural productivity and laborsaving. However, since there are some kinds of herbicides which have been used so many years, some weeds have become resistant to them and hardly destroyable weeds against which those herbicides are not or little effective have been increasing and therefore, it has been highly expected to develop herbicides having a wide herbicide spectrum and effective even against these hardly destroyable weeds.
Further, conventional herbicides often cause pollution of soil and ambient environmental pollution and, in order to prevent such environmental pollution, development of herbicides highly active and effective even in a small amount of use has been desired.
Besides, to deal with uneven propagation of weeds over a long time, herbicides having excellent effect retention, effective even by dispensation in a wide range of periods from before development of weeds to the growing stage and having a wide range of appropriate application period have been expected to be available.
Moreover, it is well known that with respect to use of conventional herbicides, chemical damages are sometimes caused on crops depending on a variety of factors relative to weather conditions such as temperature, wind, light and the like; soil conditions such as soil properties, organic compound contents in soil and the like; planting management conditions such as shallow transplantation depth, use of fragile and too long seedling, deep water control and the like; conditions for application of the chemical agent such as uneven sprinkling or excess sprinkling of herbicides and the like, so that appearance of a herbicide highly safe and free from a risk of occurrence of chemical damages on crops in any conditions has been desired.